Octane rating...95 & 93 (difference)

Ockie

Ockie

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So today I pulled into the garage and asked to be filled up (grin),

He says there aint any 93 left but my car will do great with 95 unleaded. I know it is a bit more expensive but I honestly could not be bothered to go to another garage. So I was filled up and sent on my merry way.

I checked now on wikipedia: http://en.wikipedia.org/wiki/Octane but it is written in greek. What is the diff between the two? Does that mean I can now take out a Bentley on the highway with my 1.4 Playa? :D

I watched a epidode once of CSI where somone jinxed another guys car with jet fuel and it exploded due to the high octane level. Should I be scared to start my tjorretjie tomorrow? :p
 
ocleroux said:
So today I pulled into the garage and asked to be filled up (grin),

He says there aint any 93 left but my car will do great with 95 unleaded. I know it is a bit more expensive but I honestly could not be bothered to go to another garage. So I was filled up and sent on my merry way.

I checked now on wikipedia: http://en.wikipedia.org/wiki/Octane but it is written in greek. What is the diff between the two? Does that mean I can now take out a Bentley on the highway with my 1.4 Playa? :D

I watched a epidode once of CSI where somone jinxed another guys car with jet fuel and it exploded due to the high octane level. Should I be scared to start my tjorretjie tomorrow? :p
Click to expand...

Lol,

Your car should perform better with a higher rated octane fuel. Personally I always fill up with 95, from my experience I get more km's out of a tank when driving the same, which to me justifies the price difference.

It is however not going to make your polo take on a bentley no, just run better.

I stand under correction but I believe it is also better for your car.
 
i've only seen 93 in JHB.....Durbz doesn't have it
 
I get 13.5km/l with 95 from BP as opposed to 12.5km/l or so with 93 also from BP. My car seems like their fuel the most. Last time I filled up I could only get Engen 93 and with that crap I get closer to 11km/l.
 
D3x! said:
Oh so Durbz doesn't have 93 at all? that makes more sense to me.

On the subject of which fuel we prefer, i personally stick to Sasol.
Click to expand...

Any reason for preference?
 
Cool thanks guys. What ever happened to 97? My dad always used to fill up his 7 series beemer with that? Why did they take it off the market?

Me gonna look for the first Bentley and try anyway! Highways nice and clear nowadays in Joburg with all the Vaalies harrasing the Capies! lol
 
Depends on how the car is set up. Some cars, especially performance cars will see a noticeable improvement in performance when using 95 at Reef altitudes. 95 won't damage your car, but there's not always a real benefit. If you want to take a drive down to the coast, fill up with 95, otherwise it will be slightly lethargic when you get there (due to timing being retarded to prevent engine damage due to knock).

We only get 95 at the coast due to the higher atmospheric pressure. We used to get 97 here, but that has since fallen away after leaded pump fuel was banned. 97 at the coast ~ 95 in Joburg, and 95 at the coast ~ 93 in Joburg.

So, oc, any octane fuel is OK, as long as it's unleaded. LRP is the devil!
 
Last edited:
ocleroux said:
Cool thanks guys. What ever happened to 97? My dad always used to fill up his 7 series beemer with that? Why did they take it off the market?

Me gonna look for the first Bentley and try anyway! Highways nice and clear nowadays in Joburg with all the Vaalies harrasing the Capies! lol
Click to expand...

Usually found on the coastal areas only. I don't recall 97 ever making it up to the highveld.
 
dj_jyno said:
So, oc, any octane fuel is OK, as long as it's unleaded. LRP is the devil!
Click to expand...

Really? I have seen it at the pumps....and have wondered if I should try it? My dad always used to say when they started with the whole leaded - unleaded thing...."So bietjie lood smeer die engine lekker" :)


But I guess you are right. The newer cars are designed to work on unleaded no? So me stays far away. :)
 
As Mr Dyno said, performance cars seems to see better gains with 95 over 93 than otherwise. Hell, my 2l Lancer has a fairly noticeable difference, especially when it comes to power, while the missus' Yaris is pretty much the same as far as I can tell.
 
Octane is actually a combustion retardant.

They add it into petrol to slow the explosion in the piston down so that you get a more "gradual" power cycle instead of a shorter, sharper one.

Try and visualise the piston in a car's cylinder...
okay? got the picture in your mind?

Now, when the spark plug ignites the fuel/air mix, there is an explosion! The explosion pushes the piston down and, in turn, powers the crank which delivers power to your wheels...
Now, imagine the explosion being a short, sharp burst... if you can liken it to rowing... exerting all your power in the first quarter of the rowing movement... Your power transfer is not very efficient.

By adding octane, they slow the explosion down. so that the gasses expand for longer, pushing the piston for the entire length of its stroke. Kinda like a nice, full controlled stroke with the oar... where you deliver your power evenly throughout the time the oar is in the water... the energy is transferred more efficiently.

Up in the highveld, we have about 20% less atmospheric pressure. if the pressure at sea level is 1bar, we have 0.8bar up here in jozi.
So the less pressure, the less oxygen in the fuel/air mix in the cylinder to power the explosions... So our cars perform a little worse up here. The fact that we have 95 AND 93 up here is a price factor. Fuel costs more up on the highveld coz they gotta drive it up here... so they have the "cheaper" option.

They don't offer 93 down at the coast because it'll cause "knocking".
knocking, is where the piston and the valves exceed their design force loads (due to the shorter, more intense explosion) and "knock" against the crank case and the cylinder head respectively. That is why only 95 octane is available at the coast.

97 was phased out purely because of price... Shell V-Power started it all... went from 97 to 95 and was a little cheaper but still had pretty much the same performance... so fuel manufacturers took a managerial decision to drop the premium petrol octane from 97 to 95... remember 87? Hehehe...

As for difference between brands of fuel... hahahaha! they're all pretty much the same! THEY HAVE TO BE! As per government regulations! There are no cute little dudes or fast little fishies that make one petrol better than another, because they're all refined in the SAME PLACE! kinda like the "Duff Beer" factory in the Simpsons! Any additives they claim to have, be it "Vapouron Boosters" or "Techron" is actually de-foaming agents and colourants... they ain't allowed to add ANYTHING else! Besides, why would one company add more crap in their fuel and sell it AT EXACTLY THE SAME PRICE as the next guy? They have to have the same price due to gvmt regs!

Hope the short lecture on fuel was informative! Safe Driving peeps!
 
OverKill69 said:
As for difference between brands of fuel... hahahaha! they're all pretty much the same! THEY HAVE TO BE! As per government regulations! There are no cute little dudes or fast little fishies that make one petrol better than another, because they're all refined in the SAME PLACE! kinda like the "Duff Beer" factory in the Simpsons! Any additives they claim to have, be it "Vapouron Boosters" or "Techron" is actually de-foaming agents and colourants... they ain't allowed to add ANYTHING else! Besides, why would one company add more crap in their fuel and sell it AT EXACTLY THE SAME PRICE as the next guy? They have to have the same price due to gvmt regs!
Click to expand...

Yeah. A lady at work, whose husband works at a fuel company told me that if a particular company is running low of fuel in a certain area, they just borrow from the closest depot to them irrespective of brand.
 
OverKill69 said:
Octane is actually a combustion retardant.

They add it into petrol to slow the explosion in the piston down so that you get a more "gradual" power cycle instead of a shorter, sharper one.

Try and visualise the piston in a car's cylinder...
okay? got the picture in your mind?

Now, when the spark plug ignites the fuel/air mix, there is an explosion! The explosion pushes the piston down and, in turn, powers the crank which delivers power to your wheels...
Now, imagine the explosion being a short, sharp burst... if you can liken it to rowing... exerting all your power in the first quarter of the rowing movement... Your power transfer is not very efficient.

By adding octane, they slow the explosion down. so that the gasses expand for longer, pushing the piston for the entire length of its stroke. Kinda like a nice, full controlled stroke with the oar... where you deliver your power evenly throughout the time the oar is in the water... the energy is transferred more efficiently.

Up in the highveld, we have about 20% less atmospheric pressure. if the pressure at sea level is 1bar, we have 0.8bar up here in jozi.
So the less pressure, the less oxygen in the fuel/air mix in the cylinder to power the explosions... So our cars perform a little worse up here. The fact that we have 95 AND 93 up here is a price factor. Fuel costs more up on the highveld coz they gotta drive it up here... so they have the "cheaper" option.

They don't offer 93 down at the coast because it'll cause "knocking".
knocking, is where the piston and the valves exceed their design force loads (due to the shorter, more intense explosion) and "knock" against the crank case and the cylinder head respectively. That is why only 95 octane is available at the coast.

97 was phased out purely because of price... Shell V-Power started it all... went from 97 to 95 and was a little cheaper but still had pretty much the same performance... so fuel manufacturers took a managerial decision to drop the premium petrol octane from 97 to 95... remember 87? Hehehe...

As for difference between brands of fuel... hahahaha! they're all pretty much the same! THEY HAVE TO BE! As per government regulations! There are no cute little dudes or fast little fishies that make one petrol better than another, because they're all refined in the SAME PLACE! kinda like the "Duff Beer" factory in the Simpsons! Any additives they claim to have, be it "Vapouron Boosters" or "Techron" is actually de-foaming agents and colourants... they ain't allowed to add ANYTHING else! Besides, why would one company add more crap in their fuel and sell it AT EXACTLY THE SAME PRICE as the next guy? They have to have the same price due to gvmt regs!

Hope the short lecture on fuel was informative! Safe Driving peeps!
Click to expand...

Wow....this was so flippen interesting man! thanks a lot!!!!

/cries cause there aint no cute dudes inside my engine cleaning it like they told me on the TV add!!!!!!!!

Gonna sue Caltex for false advertising!!!!!!

So, seeing that it makes the engine and explosions more effecient, does that mean you should see better fuel economy as some posters said on the first page?
 
The lowest rating that doesn't misfire is what you ought to go for. The performance differences are marginal... at least that's according to the fuel standard researchers here at work.
 
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